Vacuum packed and pressurized products have long presented problems and difficulty in removing caps from their containers. Under vacuum the lids and sealing liners are held substantially tighter than without and caps are very difficult to lift off, in the case of snap caps, or twist-off, in the case of threaded caps until the seal is broken typically without special means for doing so, and the vacuum released.
Caps on pressurized containers, on the other hand, have problems with premature cap blow-off relating to the loss of thread engagement before the internal pressure is released resulting in many personal injuries and large financial loss.